expected: |
  True,False,{"value":"1"}
query: |
  declare json string := '
  {
    "a": 1,
    "b": [3, 1]
  }';
  declare nojson string := '{a"a":6}';
  select
    is_json(json),
    is_json(nojson),
    to_json((select 1))
